N = int(input())
c = input()

num_R = c.count('R')

print(c[:num_R].count('W')) N = int(input()) N int(input()) int input() input c = input() c input() input num_R = c.count('R') num_R c.count('R') c.count c count 'R' print(c[:num_R].count('W')) print c[:num_R].count('W') [:num_R].count [:num_R] c :num_R num_R count 'W' num_R = c.count('R') c.count('R') num_R c = input() input() c N = int(input()) int(input()) N
N = int(input())
c = input()

num_R = c.count('R')

print(c[:num_R].count('W'))
